CENOZOIC POSTRIFT DOMAL UPLIFT OF NORTH-ATLANTIC MARGINS - AN ASTHENOSPHERIC DIAPIRISM MODEL

Postrift domal uplifts are a distinct feature of the northern North At lantic rifted margins, Uplifted regions (southern Norway, Finnmark, Sv albard, northern United Kingdom) occur with a typical spacing of simil ar to 900 km, The amount of domal uplift is substantial (1-2 km); ther mochronological, geomorphological, and seismic stratigraphic data sugg est a coincident Neogene onset of uplift, postdating North Atlantic br eakup and predating onset of glaciation, The Norwegian domes are chara cterized by strongly negative gravity anomalies and reduced mantle P-w ave and S-wave velocities, Previous models for uplift around the North Atlantic (e.g., glacial erosion, intraplate stresses, secondary conve ction) fail to explain the above characteristics. We present an asthen ospheric diapir model based on a Rayleigh-Taylor instability, wherein a hot ''Icelandic'' asthenosphere layer meets cold cratonic lithospher e. The generated asthenospheric diapirs and associated partial melting offer a viable explanation for updoming. Application of this model to the south Norwegian dome succesfully explains most of the currently a vailable data.